Using high-voltage power transmission lines to power an unmanned air/aerial vehicle or drone (hereinafter generally referred to as a “UAV”) is known and disclosed, for example, in U.S. patent application publication 2017/0015414 (hereinafter “Chen”), insofar as Chen discloses that power can be supplied to a UAV from a powerline, through an interface, to an energy storage system of the UAV for repowering of the energy storage system of the UAV.
In this respect, Chen broadly discloses that this can be done by one of capacitive power transfer and inductive power transfer. Chen specifically recognizes that a UAV is commonly configured with a base and one or a set of rotors to provide lift and thrust for propulsion, wherein the rotors are driven by a propulsion system having an electric motor driven by an energy storage system comprising a battery. Chen acknowledges that in such known arrangements the range and usefulness of the UAV are limited by the amount of energy available from the battery. Chen further notes that electric power is transmitted through a vast network of utility transmission systems across the country, including alternating current (AC) powerlines (e.g., utility transmission lines) supported by structures (e.g., towers), and Chen recognizes that these powerlines represent an available power source for apparatus that can be configured to access them.
The innovations in Chen are based on the use of such known utility transmission systems to enhance the range and utility of such UAVs, as well as for providing flyways or routes for such UAVs. The range is enhanced, according to Chen, by using power supplied from utility transmission systems through an interface to an energy storage system of the UAV. As explicitly stated by Chen, “the inventions generally relate to improvements to methods and systems for repowering unmanned aircraft and to improvements to unmanned aircraft and for unmanned aircraft systems and methods” (emphasis added).
Fairly characterized, Chen discloses that the transfer of energy may comprise transferring energy from an electric field to the UAV, and that the powerline produces an electric field and the aircraft is configured to extract power for repowering of the energy storage system using the electric field of the powerline; however, Chen is replete with speculation regarding how this might be done and is short on technical detail, instead taking a broad-brush approach in the written description.
Consequently, it is believed that a significant shortcoming of Chen is a failure to recognize and appreciate electric field strengths and interactions within the vicinity of powerlines. Indeed, electric field topography in the vicinity of powerlines is complex and depends on a number of factors, including the number of conducting lines and their arrangement.
For example, an exemplary powerline transmission tower 100 is seen in FIG. 1 and includes three conducting lines 102,104,106 each out of phase with the others, and two shield wires 108,110.
Another exemplary tower 100a that typically is found in power transmission systems is illustrated in FIG. 2 and, like tower 100, includes conducting lines 102,104,106 and shield lines 108,110. FIG. 3 shows yet another exemplary tower 100b. Unlike towers 100 and 100a, tower 100b includes six conducting lines comprising conducting lines 102a,104a; conducting lines 102b,104b; and conducting lines 102c,104c. Tower 100b also includes shield lines 108,110.
For use with preferred embodiments of the invention, the voltage of the powerlines of the exemplary towers preferably is 345 kV, 500 kV, or 765 kV, and the powerlines preferably are three-phase AC.
Electric field strengths within the vicinity of the powerlines of the exemplary towers are complex. For example, the electric fields of the powerlines of FIG. 1 are modeled in FIG. 4. It will be appreciated that the highest electric field strengths exist in the immediately surrounding area 112 of the conducting lines 102,104,106, and that the lowest electric field strengths exist in the furthest surrounding area 120, with intermediate field strengths existing in nested areas 114,116,118. Moreover, with reference to FIG. 4, “vicinity” of powerlines as used herein means, for a 500 kV 3 phase AC transmission line, within an area of powerlines extending thirty (30) meters to either side of the center line and upwards from ground of thirty-five (35) meters so as to encompass areas 112,114,116,118. An alternative definition used herein is the area around powerlines in which the log base 10 of the electric field in volts per meter is equal to or greater than two.
It will be appreciated from examination of the modeling seen in FIG. 4 that there exist great electric field differentials within the vicinity of powerlines. Indeed, FIG. 4 shows that the electric field strengths are around one hundred times greater in areas 112 than in the outer fringes of area 118, i.e., the difference between about a thousand volts per meter (1 kV) and ten thousand kilovolts per meter (10 kV).
To further illustrates this point, additional exemplary electric field strengths within a vicinity of powerlines also are modeled in FIG. 5. The area of the modeling in FIG. 5 encompasses thirty (30) meters to either side of a center line and upwards from ground of about (14) meters. Each of the fourteen red lines representing the root mean square value/magnitude of the x-component of the electric field is modeled at between one (1) meter and fifteen (15) meters from ground, with the difference between successive red lines representing one (1) meter in height. Similarly, each of the fourteen blue lines representing the root mean square value/magnitude of the y-component of the electric field is modeled at between one (1) meter and fifteen (15) meters from ground, with the difference between successive blue lines representing one (1) meter in height; and each of the fourteen purple lines representing the root mean square value/magnitude of the combined electric field is modeled at between one (1) meter and fifteen (15) meters from ground, with the difference between successive purple lines representing one (1) meter in height.
It will be appreciated from examination of the modeling seen in FIG. 5 that not only do there exist great electric field differentials, but that there also exist local maximums and minimums in electric field strengths, such that increasing the distance between any given two points does not necessarily increase the electric field differential between the two points. For instance, two points located a certain distance apart may have no electric field differential, but each point may have significant electric field differentials with respect to intermediate points located there between.
Additionally, while not the same topography, each of the electric field topographies found with tower 100a and tower 100b is similarly complex.
Accordingly, it is believed that embodiments of the invention represent technological improvements neither disclosed nor rendered obvious by Chen, as one or more embodiments rely upon electric field differentials unrecognized in and unappreciated by Chen. For example, one or more embodiments are believed to enable, inter alia, UAVs to make better use of electric fields within the vicinity of transmission powerlines to the extent that not only can the conventional, rechargeable energy sources of the UAVs be repowered, but actual flight along transmission powerlines can be realized in UAVs without reliance on any energy storage system. Moreover, it is believed that such technological improvements represent a new type of power source for generating electrical energy by harnessing electric fields, and that such new type of power source can be used in replacement of or in combination with conventional power sources when powering objects within high voltage electric fields.